Different types of moveable barrier operators have been sold over the years and these barrier operator systems have been used to actuate various types of moveable barriers. For example, garage door operators have been used to move garage doors and gate operators have been used to open and close gates.
Such barrier movement operators may include various mechanisms to open and close the barrier. For instance, a wall control unit may be coupled to the barrier movement operator and sends signals to a head unit thereby causing the head unit to open and close the barrier. In addition, operators often include a receiver unit at the head unit to receive wireless transmissions from a hand-held code transmitter or from a keypad transmitter, which may be affixed to the outside of the area closed by the barrier or other structure.
At times, obstructions may enter the pathways of barriers in barrier operator systems. For instance, a car or a person may enter the path of the barrier as the barrier is closing. Obstruction detection systems are used in barrier operator systems to determine whether an obstruction has entered the path of a barrier. For example, a photo detector may be used to determine whether there is an obstruction present in the pathway of the door and the movement of the door may be halted or reversed whenever an obstruction is detected.
In other examples of obstruction detection systems, an area is monitored by a video camera. The area monitored includes the pathway of a barrier and other areas outside the pathway of the barrier. In these previous systems, “obstructions” were determined to exist in the pathway of the barrier when an object entered anywhere in the field of view of the camera (i.e., whether or not the object was actually in the pathway of the barrier). Consequently, unneeded evasive actions were often performed as the result of the erroneous obstruction determinations.
In one specific example of a system that had this problem, a camera was sometimes used to monitor the area around a security gate at an entrance of a controlled area (e.g., the boarding area of an airport). While monitoring the pathway of the gate, the camera also monitored areas behind the gate (within the controlled area) and outside of the pathway of the barrier. Whenever movement was detected anywhere in the field of view of the camera, an obstruction was determined to exist. For instance, when movement was detected behind the gate (and not in the pathway of the gate), an obstruction was determined to exist when nothing was present in the pathway of the gate. Unnecessary evasive actions (e.g., stopping or reversing barrier movement) were often performed in these previous systems as a result of the false obstruction detections. Consequently, the efficiency of these systems became degraded and user frustration with the systems increased.